ABSTRACT By 2050 nearly 14 million people will suffer from Alzheimer's disease and related dementias (ADRD) in the US and minorities will be disproportionally burdened. While it is known that certain racial/ethnic groups, such as African Americans, have higher rates of dementia, reasons for disparities are unknown. Though education and occupation are robustly associated with ADRD, research on education quality and occupational complexity has primarily included only Whites or, when examining racial/ethnic differences, focused on comparisons between Whites and African Americans. We propose to examine the role of educational quality and occupational complexity on cognitive decline, ADRD, and imaging markers of vascular brain injury and neurodegeneration in a cohort with unparalleled racial/ethnic diversity. The proposed study derives measures of education quality and occupational complexity, building upon the following rich data sources at Kaiser Permanente Northern California: detailed social and physical measures from a Multiphasic Health Checkup completed during the 1960s to 1990s; electronic medical records from 1996 onward; and detailed social, cognitive, and neuroimaging measures from the Kaiser Healthy Aging and Diverse Life Experiences (KHANDLE) study assessments. KHANDLE collects the names and locations of schools attended at 1st, 6th, 9th, and 12th grades as well as college or university attended which will be linked to historical indicators of school quality. Comprehensive information collected regarding occupation enables delineation of occupational complexity in early-, mid-, and late-adulthood. Utilizing these comprehensive data sources, we are in a unique position to successfully complete the aims of the study, which are to: 1) Evaluate the roles of education quality on cognitive decline, ADRD incidence, and imaging markers of vascular brain injury and neurodegeneration in African American, White, Asian, and Latino individuals; 2) Examine the role of occupational complexity on cognitive decline, ADRD incidence, and imaging markers of vascular brain injury and neurodegeneration in this diverse cohort; 3) Delineate if patterns of educational quality and occupational complexity across the lifecourse mediate racial and ethnic disparities in ADRD, cognitive decline, and imaging markers of vascular brain injury and neurodegeneration. Utilizing a lifecourse approach, as recommended by the NIH State of the Science on Preventing Cognitive Decline, the proposed research will add vital information regarding the characteristics and timing of education quality and occupational complexity characteristics associated with ADRD and may inform future interventions aiming to improve cognition among elderly of all racial/ethnic groups. Given the marked disparities in ADRD rates by racial/ethnic groups there has never been a more critical time to understand how sociocontextual risk factors impact brain health in diverse populations.